Ahhh....That makes sense for the smaller 32k part.??For the larger DS1486 there really isn't a replacement that would work.
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I've worked this DS1486 issue for quite some time now...and there really isn't any good solution.? The DS1486 is a 128Kx8 part with the built in RTC (the 256K was a typo).?? Maxim/Dallas STOPPED production of this part some time in the 2009?timeframe from the best I can tell.? The subs that Maxim recommends are not a direct replacement.? In order to use those parts it would require the scope's firmware be modified so that it would look at the different address for the various RTC registers - not at all feasible.
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I've purchased some of these DS1486 parts?from various vendors on Ebay, and I believe those parts are fake/counterfiet for these reasons:
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1.? If Maxim stopped production in 2009, how are date codes of 2011 or 2012 possible?
2.? Several of the parts I received had pins that were quite a bit out of spec for the width - Maxim would never allow that
3.? The parts I purchased had a high fallout rate, often as high as 40-50% failure rate.? I could write a particular pattern to the SRAM area, read back, and see data miscompares.
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You might find some of the Ebay/China parts that work, but I really wonder about long term reliability.
I think a cool solution would be to make a small PCB with a DS1746 and a CPLD on it that would translate the addresses of the DS1486 to the new address of the DS1746.? But this would take a fair amount of time and hassle (as well as money to spin a PCB).
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The DS1245 idea isn't a bad idea, but like you say you would lose the clock - I wonder if the Tek firmware checks to see if the clock updates when it does its Power on self test?
